1. Field of the Invention
The present invention relates generally to a mobile communication system, and more particularly, to a receiver capable of simplifying hardware required for finger and combiner in accordance with the channel characteristics in a mobile communication system using physical channels.
2. Discussion of the Related Art
Currently, the TSG (technical specification group) that belongs to the 3GPP has recommended a RAN (radio access network) standard.
In the RAN standard, transport channels and physical channels for use in physical layers have been prescribed.
The transport channels are defined by how and with what characteristics data is transferred over an air interface. The transport channels are for services offered by a layer-1 to higher layers.
The physical channels are defined by a specified carrier frequency, scrambling code, channelization code (optional), time start and stop (for giving a duration), and relative phase (i.e., 0 or π/2) on an uplink.
FIG. 1 is a view illustrating the mapping of transport channels onto physical channels. The transport channels are mapped onto the physical channels.
Under the assumption that the mobile communication system using already known rake receivers complies with the above-described 3GPP standard, a finger and combiner of rake receivers is configured as shown in FIG. 2.
FIG. 2 is a block diagram illustrating a conventional finger and combiner of rake receivers that satisfies the 3GPP standard.
Referring to FIG. 2, the finger and combiner of the rake receivers separates signals of one downlink physical channel received through several paths, demodulates and dispreads separated channels of the respective paths, and then combines demodulated and dispread channels.
Fingers take charge of the demodulation and dispreading process, and combiners 101˜107 combine the paths.
However, according to the conventional finger and combiner, a configuration for combining the respective receiving paths with respect to all downlink physical channels being used should be provided.
Specifically, fingers should be provided for all the downlink physical channels inputted through respective receiving paths, and combiners 101˜107 for combining outputs of the fingers should also be provided as many as the number of channels.
Currently, the rake receiver provided in the communication system separates signals of one channel inputted with time differences into three paths in the order of a power strength, and thus fingers as many as three times the number of channels and combiners 101˜107 as many as the total number of channels are required to process all the downlink physical channels.
FIG. 2 exemplifies the use of seven downlink physical channels. In this case, the required number of fingers is 21 (i.e., 7*3), and the required number of combiners is 7.
Further, in case that the rake receiver is provided with searchers, i.e., fingers for continuously measuring the strength of a pilot signal, 22 fingers are required in total.
Consequendy, the conventional rake receivers have drawbacks in that in order to process the downlink physical channels of a mobile communication system, the whole hardware scale required for the fingers and combiner is increased. Also, since lots of logical operators used for the fingers and combiner are required, the circuit configuration is complicated, and the manufacturing cost is increased.